Certain formamidine dithiophosphates and phosphonates and their use as insecticides

ABSTRACT

Compounds having the formula ##STR1## in which R 1  is lower alkyl or lower alkoxy, R 2  is lower alkoxy or methylthio-substituted lower alkoxy, and R 3  is ##STR2## R 4  and R 5  are lower alkyl, m is 1 or 2 and n is 0 or an integer from 1 to 4. The compounds have utility as insecticides and acaricides.

DESCRIPTION OF THE INVENTION

This invention relates to certain novel formamidine dithiophosphates and-phosphonates. More particularly, this invention relates to certainnovel formamidine dithiophosphates and -phosphonates having the formula##STR3## in which R₁ is lower alkyl or lower alkoxy, R₂ is lower alkoxyor methylthio-substituted lower alkoxy, R₃ is ##STR4## R₄ and R₅ arelower alkyl, m is 1 or 2, and n is 0 or an integer from 1 to 4.

By the terms "lower alkyl" and "lower alkoxy" are meant such groupscontaining from 1 to about 6 carbon atoms, preferably from 1 to about 4carbon atoms, for instance, methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec.-butyl, tert.-butyl, amyl, hexyl and the like, andmethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy,sec.-butoxy, and the like.

In one embodiment, R₁ is lower alkyl while R₂ is lower alkoxy; thecompounds are phosphonates.

In another embodiment, both R₁ and R₂ are lower alkoxy; the compoundsare phosphates.

When R₃ is ##STR5## R₄ and R₅ may be the same or different lower alkylmoieties.

In another aspect, the invention also relates to a process or method forcontrolling insects by applying to the insect or the habitat thereof aninsecticidally effective amount of a compound having the formula##STR6## in which R₁ is lower alkyl or lower alkoxy, R₂ is lower alkoxyor methylthio-substituted lower alkoxy, R₃ is ##STR7## R₄ and R₅ arelower alkyl, m is 1 or 2 and n is 0 or an integer from 1 to 4.

Various methods of controlling insects involve the use of the variousembodiments of the compounds of the present invention mentioned above.

The compounds of the present invention are prepared in general by thefollowing method:

The novel compounds of this invention may be prepared by a three-stepprocess. In the first step, an amine having the formula R₃ H is reactedwith an acetal of a formamide, for instance, N, N-dimethylformamidedimethyl acetal, to form the corresponding N-formyl acetal: ##STR8##

In the second step, the N-formyl acetal is reacted with achloroalkylamide to produce a formamidine: ##STR9##

Finally, the formamidine is reacted with a dithiophosphate or-phosphonate to produce the desired compound: ##STR10##

The following examples demonstrate the preparation of two compounds ofthe present invention

a. 85 g (1 mole) of piperidine and 119 g (1 mole) ofN,N-dimethylformamide dimethyl acetal were mixed and warmed slowly withstirring. After 3 hours, the reaction product was fractionallydistilled. There was obtained 76.8 g (0.48 mole, 48% of theoreticalyield) N-formylpiperidine dimethyl acetal.

b. 48 g (0.3 mole) of the acetal produced in step (a) was mixed with 0.3mole 2-chloroacetamide and 200 ml benzene and the mixture warmed toabout 35° C. with stirring for 1/2 hour. The benzene was removed undermild vacuum at about 30° C. for 1 hour. The product was stripped,yielding 60 g (0.39 mole, 106% of theoretical yield) ofN-chloroacetylformimino-piperidine, as a semi-solid product.

c. To 23.8 g (0.14 mole) 0-ethyl, ethyldithiophosphonic acid in 120 mlof benzene, being cooled in an ice bath, was added 14.14 g (0.14 mole)triethylamine in 50 ml benzene, followed by 26.4g(0.14 mole) of theN-chloroacetylformimino-piperidine from step (b), also in 50 ml benzene.The mixture was heated under reflux for 2 hours, and stripped. Theproduct was dissolved in ether and water; the ether solution was washedwith water, dried over MgSO₄, decolorized and stripped. There wasobtained 34.5 g (0.107 mole, 73% of theoretical yield) (O-ethyl ethyldithiophosphonylacetyl)formimino-piperidine (compound 9 of the followingTable I), n_(D) ³⁰ 1.5762.

d. 22.32 g (0.12 mole) O,O'-diethyl dithiophosphoric acid was mixed with50 ml of a 25% solution of sodium methoxide in methanol (i.e., 0.12 molesodium methoxide). The mixture was stirred and stripped, producing 24 gof a white powder, believed to be the sodium salt of the acid. The whitepowder was stirred in 120 ml acetone and 22.6 g (0.12 mole)N-chloroacetylformimino-piperidine, prepared in step (b), dissolved in100ml acetone, was added. The mixture was refluxed for 2 hours andstripped. The residue was dissolved in ether and water, the ethersolution washed with water, dried over MgSO₄, decolorized and stripped.There was obtained 31.5 g (0.093 mole, 77.6% of theoretical yield) (O,O'diethyldithiophosphoryl)formimino-piperidine (compound 10 of Table I),n_(D) ³⁰ 1.5592.

The following table 1 lists representative compounds of the presentinvention which may be prepared according to the above procedures.

                  Table 1                                                         ______________________________________                                         ##STR11##                                                                    Compound                                                                              m      R.sub.1  R.sub.2   R.sub.3                                                                              n.sup.30.sub.D                       ______________________________________                                        1       1     C.sub.2 H.sub.5 O                                                                      C.sub.2 H.sub.5 O                                                                       N(CH.sub.3).sub.2                                                                     1.5521                               2       1     C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5 O                                                                       N(CH.sub.3).sub.2                                                                     1.5628                               3       1     CH.sub.3 O                                                                             CH.sub.3 O                                                                              N(CH.sub.3).sub.2                                                                     1.5302                               4       1     C.sub.2 H.sub.5                                                                        i-C.sub.3 H.sub.7 O                                                                     N(CH.sub.3).sub.2                                                                     1.5573                               5       1     C.sub.2 H.sub.5                                                                        CH.sub.3 O                                                                              N(CH.sub.3).sub.2                                                                     1.5770                               6       1     C.sub.2 H.sub.5                                                                        CH.sub.3 S(CH.sub.2).sub.2 0                                                            N(CH.sub.3).sub.2                                                                     1.6057                               7       1     C.sub.2 H.sub.5                                                                        s-C.sub.4 H.sub.9 O                                                                     N(CH.sub.3).sub.2                                                                     1.5528                               8       1     C.sub.2 H.sub.5                                                                        CH.sub.3 O                                                                               ##STR12##                                                                            1.5640                               9       1     C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5 O                                                                        ##STR13##                                                                            1.5762                               10      1     C.sub.2 H.sub.5 O                                                                      C.sub.2 H.sub.5 O                                                                        ##STR14##                                                                            1.5592                               11      1     C.sub.2 H.sub.5                                                                        i-C.sub.3 H.sub.7 O                                                                      ##STR15##                                                                            1.5478                               12      1     C.sub.2 H.sub.5                                                                        s-C.sub.4 H.sub.9 O                                                                      ##STR16##                                                                            1.5500                               13      1     C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5 O                                                                        ##STR17##                                                                            1.5656                               14      1     C.sub.2 H.sub.5 O                                                                      C.sub.2 H.sub.5 O                                                                        ##STR18##                                                                            1.5459                               15      1     C.sub.2 H.sub.5                                                                        CH.sub.3 O                                                                               ##STR19##                                                                            1.5811                               16      1     C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5 O                                                                       N(C.sub.2 H.sub.5).sub.2                                                              1.5821                               17      1     C.sub.2 H.sub.5 O                                                                      C.sub.2 H.sub.5 O                                                                       N(C.sub.2 H.sub.5).sub.2                                                              1.4969                               18      2     C.sub.2 H.sub.5                                                                        C.sub.2 H.sub.5 O                                                                       N(CH.sub.3).sub.2                                                                     1.5580                               ______________________________________                                    

Insecticidal Evaluation Tests

The following insect species were used in evaluation tests forinsecticidal activity.

1. Housefly (HF) -- Musca domestica (Linn.)

2. German Roach (GR) -- Blatella germanica (Linn.)

3. Lygus Bug (LB) -- Lygus hesperus (Knight)

4. Bean Aphid (BA) -- Aphis fabae (Scop.)

5. Green Peach Aphid (GPA) -- Myzus persicae (Sulzer)

6. Salt Marsh Caterpillar (SMC) -- Estigmene acrea (Drury)

7. Cabbage Looper (CL) -- Trichoplusia ni (Hubner)

8. Tobacco Bud Worm (TBW) -- Heliothis virescens (F.)

9. Southern House Mosquito (MOS) -- Culex pipiens quinquefasciatus (Say)

The insecticidal evaluation tests were conducted as follows:

Housefly: Test compounds were diluted in acetone and aliquots pipettedonto the bottom of 55 × 15 mm aluminum dishes. To insure even spreadingof the chemical on the bottom of the dishes, 1 ml of acetone containing0.02% peanut oil was also added to each dish. After all solvents hadevaporated, the dishes were placed in circular cardboard cagescontaining 25 female houseflies, 1 to 2 days old. The cages were coveredon the bottom with cellophane and on top with tulle netting, and eachcontained a sugar-water saturated cotton plug for maintenance of theflies. Mortality was recorded after 48 hours. Test levels ranged from100 μg/25 female houseflies down to that at which approximately 50%mortality occurred. The LD-50 values are expressed below in Table IIunder the heading HF, in terms of μg of the test compound per 25 femaleflies.

German Cockroach: Test compounds were diluted in a 50-50 acetone-watersolution. 2 cc of the solution were sprayed through a DeVilbiss type EGAhand spray gun into circular cardboard cages containing 10 one-month-oldGerman cockroach nymphs. The test cages were covered on the bottom withcellophane and on the top with tulle netting. Percent mortality wasrecorded 7 days later. Test concentrations ranged from 0.1% down to thatat which approximately 50% mortality occurred. LD-50 values areexpressed below in Table II under the heading GR in terms of percent ofthe test compound in the sprayed solution.

Lygus Bug: Test compounds were diluted in a 50-50 acetone-watersolution. 2 cc of the solution were sprayed through a DeVilbiss type EGAhand spray gun into circular cardboard cages containing 1 string beanpod and 10 adult lygus bugs. The test cages were covered on the bottomwith cellophane and on the top with tulle netting. Percent mortality wasrecorded 48 hours later. Test concentrations ranged from 0.05% down tothat at which approximately 50% mortality occurred. LD-50 values areexpressed below in Table II under the heading LB in terms of percent ofthe test compound in the sprayed solution.

Black Bean Aphid: Nasturtium plants (Tropaeolum sp.), approximately 5 cmtall, were transplanted into sandy loam soil in 3-inch clay pots andinfested with 25-50 black bean aphids of mixed ages. 24 hours later theywere sprayed to the point of runoff with 50-50 acetone-water solutionsof the test chemicals. Treated plants were held in the greenhouse andmortality was recorded after 7 days. Test concentrations ranged from0.05% down to that at which 50% mortality occurred. LD-50 values areexpressed below in Table II under the heading BA in terms of percent ofthe test compound in the sprayed solution.

Green Peach Aphid: Radish plants (Rhaphanus sativus), approximately 2 cmtall, were transplanted into sandy loam soil in 3-inch clay pots andinfested with 25-50 green peach aphids of mixed ages. 24 hours laterthey were sprayed to the point of runoff with 50-50 acetone-watersolutions of the test chemicals. Treated plants were held in thegreenhouse and mortality was recorded after 48 hours. Testconcentrations ranged from 0.05% down to that at which 50% mortalityoccurred. LD-50 values are expressed below in Table II under the headingGPA in terms of percent of the test compound in the sprayed solution.

Salt-Marsh Caterpillar: Test compounds were diluted in a 50-50acetone-water solution. Sections of curly dock (Rumex crispus) leaves,approximately 1 × 1.5 inches, were immersed in the test solution for 2-3seconds and placed on a wire screen to dry. The dried leaves were placedin petri dishes containing a moistened piece of filter paper andinfested with 5 second-instar salt-marsh caterpillar larvae. Mortalityof the larvae was recorded 48 hours later, and a piece of syntheticmedia was added to dishes containing survivors. These were then held for5 additional days to observe for any delayed effects of the testchemicals.

Test concentrations ranged from 0.05% down to that at whichapproximately 50% mortality occurred. LD-50 values are expressed belowin Table II under the heading SMC in terms of percent of the testcompound in the solution.

Cabbage Looper: Test compounds were diluted in a 50-50 acetone-watersolution. Cotyledons of hyzini squash (Calabacita abobrinha),approximately 1 × 1.5 inches, were immersed in the test solutions for2-3 seconds and placed on a wire screen to dry. The dried leaves wereplaced in petri dishes containing a moistened piece of filter paper andinfested with five second-instar cabbage looper larvae. Mortality of thelarvae was recorded 48 hours later, and a piece of synthetic media addedto dishes containing survivors. These were then held for 5 additionaldays to observe for any delayed effects of the test chemicals.

Test concentrations ranged from 0.1% to that at which approximately 50%mortality occurred. LD-50 values are expressed below in Table II underthe heading CL in terms of percent of the test compound in the solution.

Tobacco Budworm: Test compounds were diluted in a 50-50 acetone-watersolution. Sections of Romaine lettuce (Latuca sativa) leaves,approximately 1 × 1.5 inches, were immersed in the test solutions for2-3 seconds and placed on a wire screen to dry. The dried leaves wereplaced in petri dishes containing a moistened piece of filter paper andinfested with five second-instar tobacco budworm larvae. Mortality ofthe larvae was recorded 48 hours later, and a piece of synthetic mediaadded to dishes containing survivors. These were then held for fiveadditional days to observe for any delayed effects of the testchemicals.

Test concentrations ranged from 0.1% to that at which approximately 50%mortality occurred. LD-50 values are expressed below in Table II underthe heading TBW in terms of percent of the test compound in thesolution.

Southern House Mosquito Larvae (Culex pipiens quinquefasciatus Say):Insecticidal activity was determined using third instar larvae of themosquito Culex pipiens quinquefasciatus. Ten larvae were placed in a sixounce paper cup containing 100 ml. of an aqueous solution of the testchemical. The treated larvae were stored at 70° F, and 48 hours laterthe mortality was recorded. Test concentrations ranged from 0.5 down tothat at which approximately 50% mortality occurred. LD-50 values areexpressed below in Table II under the heading MOS in terms of ppm of thetest compound in the solution.

Acaricidal Evaluation Test

The two-spotted mite (2SM), Tetranychus urticae (Koch), was employed intests for miticides. The test procedure was as follows:

Pinto bean plants (Phaseolus sp.) approximately 10 cm tall, weretransplanted into sandy loam soil in 3-inch clay pots and thoroughlyinfested wth two-spotted mites of mixed ages and sexes. 24 hours later,the infested plants were inverted and dipped for 2-3 seconds in 50-50acetone-water solutions of the test chemicals. Treated plants were heldin the greenhouse, and 7 days later mortality was determined for boththe adult mites and the nymphs hatching from eggs which were on theplants at the time of treatment. Test concentrations ranged from 0.05%down to that at which 50% mortality occurred. LD-50 values are expressedbelow in Table II under the headings 2SM-PE (i.e., post-embryonic) and2SM-Eggs, in terms of percent concentration of the test compound in thesolution.

Systemic Evaluation Test

This test evaluates the root absorption and upward translocation of thecandidate systemic compound. The two-spotted mite (2SM) Tetranychusurticae, (Koch) and the Bean Aphid (BA) -- Aphis fabae (Scop.) wereemployed in the test for systemic activity. Tests were conducted asfollows:

Two-Spotted Mite: Test chemicals were dissolved in acetone and aliquotsdiluted in 200 cc of water in glass bottles. Two pinto bean plants(Phaseolus sp.), with expanded primary leaves, were supported in eachbottle by cotton plugs, so that their roots and stems were immersed inthe treated water. The plants were then infested with 75-100 two-spottedmites of various ages and sexes. One week later the mortality of theadult mites and nymphs was recorded. Test concentrations in the mediumranged from 10 ppm down to that at which 50% mortality occurred.

Black Bean Aphid: Test chemicals were diluted in acetone and aliquotsthoroughly mixed into 500 grams of dry, sandy loam soil. The treatedsoil was placed in a pint-sized carton and a nasturtium plant(Tropaeolum sp.) approximately 5 cm tall was transplanted into eachcarton. The plants were then infested with approximately 25 black beanaphids of mixed ages and placed in the greenhouse. 7 days latermortality was recorded. Test concentrations ranged from 10 ppm down tothat at which approximately 50% mortality occurred.

LD-50 values are expressed below in Table II under the headings 2SM-Sand BA(S) respectively, in terms of percent concentration of the testcompound.

                                      Table 2                                     __________________________________________________________________________                                                      2-SM                        Compound                                                                            HF    GR  LB   BA    BA(S)                                                                             GPA                                                                              SMC CL  TBW MOS PE  E                       No.   (μg)                                                                             (%) (%)  (%)   (ppm)                                                                             (%)                                                                              (%) (%) (%) (ppm)                                                                             (%) (%) (ppm)               __________________________________________________________________________    1     4     .03 >.05 .0008 0.8 .005                                                                             >.05                                                                              >0.1                                                                              --  >1  <.05                                                                              <.05                                                                              3                   2     0.3   .003                                                                              .003 .0003 0.3 .001                                                                             >.05                                                                              >0.1                                                                              --  >1  .005                                                                              .005                                                                              0.5                 3     80    >0.1                                                                              >.05 >.05  --   --                                                                              >.05                                                                              >0.1                                                                              --  >1  <.05                                                                              <.05                                                                              >10                 4     18    .005                                                                              .01  .0003 0.3 .001                                                                             >.05                                                                              --  --  0.6 .01 .03 3                   5     0.09  .008                                                                              .01  .0008 3   .001                                                                             >.05                                                                              .05 .05 1   <.05                                                                              <.05                                                                              3                   6     >100  >0.1                                                                              .03  .001  1   .01                                                                              >.05                                                                              --  --  0.2 <.05                                                                              <.05                                                                              >10                 7     30    .01 .03  .0008 1   .008                                                                             >.05                                                                              --  --  0.6 <.05                                                                              <.05                                                                              5                   8     0.8   .01 .005 .001  1   .008                                                                             .05 >0.1                                                                              >0.1                                                                              >1  .01 .03 0.5                 9     1     .008                                                                              .0008                                                                              .0008 0.3 .001                                                                             >.05                                                                              >0.1                                                                              0.1 >1  .005                                                                              .03 0.3                 10    5     .08 .03  .0008 1   .01                                                                              >.05                                                                              >0.1                                                                              >0.1                                                                              >1  <.05                                                                              <.05                                                                              3                   11    5     .008                                                                              .005 .0001 0.1 .003                                                                             .05 0.1 .08 1   .003                                                                              >.05                                                                              1                   12    27    .01 .01  .00008                                                                              0.3 .01                                                                              >.05                                                                              0.1 .05 1   <.05                                                                              <.05                                                                              5                   13    0.75  .005                                                                              .001 .00005                                                                              .03 .003                                                                             .05 .08 .05 0.8 .003                                                                              .03 .03                 14    9     >0.1                                                                              .05  .003  3   .05                                                                              >.05                                                                              --  --  >1  .05 <.05                                                                              5                   15    3.3   .005                                                                              .002 .003  10  .002                                                                             >.05                                                                              .05 .05 >1  .003                                                                              .03 2                   16    3.7   .005                                                                              .003 .0001 1   .002                                                                             .05 .03 0.1 1   .002                                                                              .03 0.8                 17    20    >0.1                                                                              >.05 .003  10  .05                                                                              >.05                                                                              >0.1                                                                              >0.1                                                                              >1  <.05                                                                              <.05                                                                              >10                 18    40    >0.1                                                                              >.05 .0003 5   .005                                                                             >.05                                                                              >0.1                                                                              >0.1                                                                              >1  .05 <.05                                                                              --                  __________________________________________________________________________

The compounds of this invention are generally embodied into a formsuitable for convenient application. For example the compounds can beembodied into pesticidal compositions which are provided in the form ofemulsions, suspensions, solutions, dusts and aerosol sprays. In general,such compositions will contain, in addition to the active compound, theadjuvants which are found normally in pesticide preparations. In thesecompositions, the active compounds of this invention can be employed asthe sole pesticide component or they can be used in admixture with othercompounds having similar utility. The pesticide compositions of thisinvention can contain, as adjuvants, organic solvents, such as sesameoil, xylene range solvents, heavy petroleum, etc.; water; emulsifyingagents; surface active agents; talc; pyrophyllite, diatomite; gypsum;clays, propellants, such as dichlorodifluoromethane, etc. If desired,however, the active compounds can be applied directly to feedstuffs,seeds, etc., upon which the pests feed. When applied in such a manner,it will be advantageous to use a compound which is not volatile. Inconnection with the activity of the presently disclosed pesticidalcompounds, it should be fully understood that it is not necessary thatthey be active as such. The purposes of this invention will be fullyserved in the compound is rendered active by external influences, suchas light or by some physiological action which occurs when the compoundis ingested into the body of the pest.

The precise manner in which the pesticidal compositions of thisinvention are used in any particular instance will be readily apparentto a person skilled in the art. Generally, the active pesticide compoundwill be embodied in the form of a liquid composition; for example, anemulsion, suspension, or aerosol spray. While the concentration of theactive pesticide in the present compositions can vary within rather widelimits, ordinarily the pesticide compound will comprise between about0.01 and about 80% by weight of the composition.

What is claimed is:
 1. A compound having the formula ##STR20## in whichR₁ is lower alkyl or lower alkoxy, R₂ is lower alkoxy, or methylthio -substituted lower alkoxy, m is 1 or 2 and n is 0 or an integer from 1 to4.
 2. A compound according to claim 1 in which R.sub. is lower alkyl. 3.A compound according to claim 2 in which R₁ is ethyl.
 4. A compoundaccording to claim 1 in which R₁ is lower alkoxy.
 5. A compoundaccording to claim 4 in which R₁ is methoxy.
 6. A compound according toclaim 4 in which R₁ is ethoxy.
 7. A compound according to claim 1 inwhich R₂ is lower alkoxy.
 8. A compound according to claim 7 in which R₂is methoxy.
 9. A compound according to claim 7 in which R₂ is ethoxy.10. A compound according to claim 7 in which R₂ is isopropoxy.
 11. Acompound according to claim 7 in which R₂ is sec.-butoxy.
 12. A compoundaccording to claim 1 in which R₂ is methylthioethoxy.
 13. A compoundaccording to claim 1 in which R₁ is lower alkyl and R₂ is lower alkoxy.14. A compound according to claim 13 in which R₁ is ethyl and R₂ isethoxy.
 15. A compound according to claim 1 in which R₁ and R₂ are bothlower alkoxy.
 16. A compound according to claim 15 in which R₁ and R₂are both ethoxy.
 17. A compound according to claim 1 in which n is 3.18. A compound according to claim 1 in which R₁ is ethyl, R₂ is methoxy,m is 1 and n is
 3. 19. A compound according to claim 1 in which R₁ isethyl, R₂ is ethoxy, m is 1 and n is
 3. 20. A compound according toclaim 1 in which R₁ and R₂ are both ethoxy, m is 1 and n is
 3. 21. Acompound according to claim 1 in which R₁ is ethyl, R₂ is isopropoxy, mis 1 and n is
 3. 22. A compound according to claim 1 in which R₁ isethyl, R₂ is sec.-butoxy, m is 1 and n is
 3. 23. A method forcontrolling insects comprising applying to the nsect or the habitatthereof an insecticidally effective amount of a compound having theformula ##STR21## in which R₁ is lower alkyl or lower alkoxy, R₂ islower alkoxy or methylthio-substituted lower alkoxy, m is 1 or 2 and nis 0 or any integer from 1 to
 4. 24. A method according to claim 23 inwhich R₁ is lower alkyl.
 25. A method according to claim 24 in which R₁is ethyl.
 26. A method according to claim 23 in which R₁ is loweralkoxy.
 27. A method according to claim 26 in which R₁ is methoxy.
 28. Amethod according to claim 26 in which R₁ is ethoxy.
 29. A methodaccording to claim 23 in which R₂ is lower alkoxy.
 30. A methodaccording to claim 29 in which R₂ is methoxy.
 31. A method according toclaim 29 in which R₂ is ethoxy.
 32. A method according to claim 29 inwhich R₂ is isopropoxy.
 33. A method according to claim 29 in which R₂is sec.-butoxy.
 34. A method according to claim 23 in which R₂ ismethylthioethoxy.
 35. A method according to claim 23 in which R₁ islower alkyl and R₂ is lower alkoxy.
 36. A method according to claim 35in which R₁ is ethyl and R₂ is ethoxy.
 37. A method according to claim23 in which R₁ and R₂ are both lower alkoxy.
 38. A method according toclaim 37 in which R₁ and R₂ are both ethoxy.
 39. A method according toclaim 23 in which n is
 3. 40. A method according to claim 23 in which R₁is ethyl, R₂ is ethoxy, m is 1 and n is
 3. 41. A method according toclaim 23 in which R₁ is ethyl, R₂ is isopropoxy, m is 1, and n is
 3. 42.A method according to claim 23 in which R₁ is ethoxy, R₂ is ethoxy, m is1 and n is
 3. 43. An insecticidal composition comprising:a. aninsecticidally effective amount of a compound having the formula##STR22## in which R₁ is lower alkyl or lower alkoxy, R₂ is lower alkoxyor methylthio-substituted lower alkoxy, m is 1 or 2 and n is 0 or aninteger from 1 to 4, and (b) an inert carrier.